1. Field of the Invention
The present invention is related to a probe card, and more particularly, to circuit patterns positioned on a printed circuit board (PCB) of a probe card.
2. Description of the Prior Art
In the semiconductor industry, an integrated circuit (IC) is obtained by sequentially ongoing IC design, semiconductor processes, and fabrication of the IC etc. After completion of these procedures, a probing card is used to perform multi-probe processes by contacting bonding pads. Only the dies qualified in the test or repaired dies are entered into subsequent bonding and packaging processes, and the packaged dies must still undergo a final test for satisfaction check.
Generally speaking, testing devices require several main instruments such as probe cards, probers, testers. A probe card is an interface between an electronic test system and a device under test (DUT), for example, a tester and a die.
A prober is usually responsible for loading and unloading the DUT from its carrier and is equipped with automatic pattern recognition optics capable of aligning the DUT with sufficient accuracy to ensure accurate registration between the pads, such as bonding pads and the tips of the probe needles. A tester is responsible for sending electronic signals to the DUT. A picoprober can also be used to validate the accuracy of circuits on the DUT.
The probe card can be seen as an interface between the DUT and the tester. The circuit pattern on the PCB of the probe card has different designs according to DUTs with different IC designs. In addition, the probe card includes three different probe needle types: a top-side needle, a bottom-side needle and a both-side needle. In this way, the QC employee can test different regions on the DUT by the picoprober.
For a die with the same IC design, the PCB of a conventional probe card is specially designed for the top-side needle test and bottom-side needle test. However, when utilizing the both-side needle test, another PCB with a different design is needed for a conventional probe card.
FIG. 1 depicts a die 10 under test, wherein a first solder pad 12 and a second solder pad 14 are positioned on the die 10. According to the location of the first bonding pad 12 and the second bonding pad 14, the die 10 can be divided into regions 16, 17, 18. FIG. 2a depicts the circuit patterns on the PCB of the probe card with a top-side needle or bottom-side needle according to the prior art. FIG. 2b depicts the circuit patterns on the PCB of the probe card with a both-side needle according to the prior art.
Please refer to FIGS. 1 and 2a together. As shown in FIG. 2a, a PCB 21 on the probe card 20 is divided into regions 22, 24. The circuit pattern in the region 22 corresponds to the circuit connected to the first bonding pad 12 and the second bonding pad 14, wherein the circuit connected to the first bonding pad 12 and the second bonding pad 14 is interlaced in the region 22. In addition, the circuit pattern in the region 24 corresponds to the circuit pattern in the region 22.
The probe card 20 mentioned above is used for a top-side needle test and a bottom-side needle test. When running the top-side needle test, a plurality of cables will connect to the region 22 in order to connect the probe card 20 with a tester. In this way, the regions 16, 17 will be obstructed by the cables, therefore, the picoprober can only pin the region 18. When running the bottom-side needle test, a plurality of cables will connect to the region 24 in order to connect the probe card 20 with a tester. In this way, the regions 17, 18 will be obstructed by the cables, therefore, the picoprober can only pin the region 16. If the region 17 is tested by running the both-side needle test, the regions 22, 24 need to be connected to the cables. In this way, space for the picoprober is blocked by cables, so the region 17 may have a problem when undergoing the picoprober test.
Therefore, another probe card with a different PCB is needed in order to test the region 17. Please refer to FIGS. 1 and 2b together. As shown in FIG. 2b, a PCB 31 on the probe card 30 is divided into regions 32, 34, 36, 38. The circuit pattern in the region 32 corresponds to the circuit connected to the first bonding pad 12. The circuit pattern in the region 34 corresponds to the circuit connected to the second bonding pad 12. The circuit connected to the first bonding pad 12 is positioned separately from the circuit connected to the second bonding pad 14. Unlike the probe card 20, the circuit connected to the first bonding pad 12 and the circuit connected to the second bonding pad 14 are interlaced together. In addition, the circuit pattern in the region 38 corresponds to the circuit pattern in the region 32; the circuit pattern in the region 36 corresponds to the circuit pattern in the region 34. The probe card 30 mentioned above is used to run the both-side needle test according to the prior art. When testing the region 17, the regions 32, 34 are connected to cables, and the space on the regions 36, 38 can be spare for the picoprober. The region 17 can also be tested by connecting the regions 36, 38 to cables, and the space on the regions 32, 34 can be used by the picoprober.
However, according to the prior art, at least two different PCBs are needed for testing the same IC design, which is time consuming and expensive.